Last visit was: 23 Apr 2026, 04:51 It is currently 23 Apr 2026, 04:51
Home
Messages
Tests
Schools
Events
Close
GMAT Club Daily Prep
Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized
for You

we will pick new questions that match your level based on your Timer History

Track
Your Progress

every week, we’ll send you an estimated GMAT score based on your performance

Practice
Pays

we will pick new questions that match your level based on your Timer History
Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.
Go to My Error Log Learn more
Close
Request Expert Reply
Confirm Cancel
Back to Forum
Create Topic
Sub 505 (Easy)|   Sequences|      
User avatar
Bunuel
User avatar
Math Expert
Joined: 02 Sep 2009
Last visit: 23 Apr 2026
Posts: 109,776
Own Kudos:
810,755
Given Kudos: 105,853
Products:
GMAT Club Tests Forum Quiz
Expert
Expert reply
Active GMAT Club Expert! Tag them with @ followed by their username for a faster response.
Posts: 109,776
Kudos: 810,755
A sequence of numbers is given by the rule an = (an – 1)^2. What is a5 29 Oct 2017, 01:56
Kudos
Add Kudos
Bookmarks
Bookmark this Post
00:00
Start Timer
Pause Timer
Resume Timer
Show Answer
Hide
Show
History
D
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!

Difficulty:

5% (low)

Question Stats:

81% (00:55) correct 19% (01:04) wrong based on 140 sessions

History

Date
Time
Result
Not Attempted Yet
A sequence of numbers is given by the rule \(a_n = (a_{n – 1})^2\). What is \(a_5\)?

(1) \(a_1 = –1\)
(2) \(a_3 = 1\)
ShowHide Answer
Official Answer
D
User avatar
chetan2u
User avatar
GMAT Expert
Joined: 02 Aug 2009
Last visit: 22 Apr 2026
Posts: 11,229
Own Kudos:
44,999
Given Kudos: 335
Status:Math and DI Expert
Location: India
Concentration: Human Resources, General Management
GMAT Focus 1: 735 Q90 V89 DI81
Products:
My Reviews
Expert
Expert reply
GMAT Focus 1: 735 Q90 V89 DI81
Posts: 11,229
Kudos: 44,999
A sequence of numbers is given by the rule an = (an – 1)^2. What is a5 29 Oct 2017, 04:36
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Bunuel
A sequence of numbers is given by the rule \(a_n = (a_{n – 1})^2\). What is \(a_5\)?

(1) \(a_1 = –1\)
(2) \(a_3 = 1\)
Show more

\(a_n = (a_{n – 1})^2\) tells us that each term is linked to another term..
so knowing ANY number in the sequence can give us the value of ALL terms in the sequence ..

we are looking for \(a_5\), so knowing any other term will help us in knowing it...

Both statements give us one value of a term, so EACH statement is sufficient

D
User avatar
A sequence of numbers is given by the rule an = (an – 1)^2. What is a5 29 Oct 2017, 10:57
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Both Statements are sufficient.

If a1 is given we can calculate a2,a3,a4 and then a5.

If a3 is given, we can calculate a4 and then a5.

IMO:D
User avatar
DarleneTran
User avatar
Joined: 31 Dec 2017
Last visit: 30 Mar 2020
Posts: 50
Own Kudos:
27
Posts: 50
Kudos: 27
A sequence of numbers is given by the rule an = (an – 1)^2. What is a5 08 Jul 2019, 23:59
Kudos
Add Kudos
Bookmarks
Bookmark this Post
A sequence of numbers is given by the rule an=(an–1)2an=(an–1)2. What is a5?

(1) a1=–1
(2) a3=1
----------
We are given how the sequence is distributed, and now we need to find out the value of the 5th term
ST1: We have the value of the 1st term, so we can easily find the value of the 2nd term and the following terms till 5th term--->Sufficient
ST2: We know the value of the 3rd term, also how the sequence is distributed, so we can easily find the 5th term--->Sufficient.
----->The answer is D
User avatar
Kinshook
User avatar
Major Poster
Joined: 03 Jun 2019
Last visit: 23 Apr 2026
Posts: 5,986
Own Kudos:
5,858
Given Kudos: 163
Location: India
Schools: HBS '26 CBS '26 Wharton '26
GMAT 1: 690 Q50 V34
WE:Engineering (Transportation)
Products:
My Reviews
Schools: HBS '26 CBS '26 Wharton '26
GMAT 1: 690 Q50 V34
Posts: 5,986
Kudos: 5,858
A sequence of numbers is given by the rule an = (an – 1)^2. What is a5 09 Jul 2019, 02:25
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Bunuel
A sequence of numbers is given by the rule \(a_n = (a_{n – 1})^2\). What is \(a_5\)?

(1) \(a_1 = –1\)
(2) \(a_3 = 1\)
Show more

Statement 1:
\(a_1 = -1 => a_2 =1 = a_3 =a_4 =a_5 =1\) SUFFICIENT

Statement 2:
\(a_3=1=a_4=a_5=1\) SUFFICIENT

Either statement is SUFFICIENT.

IMO D
Moderators:
Bunuel
Math Expert
109776 posts
kingbucky
498 posts
Gmat860sanskar
212 posts